Increased 18F-FDG uptake in the trapezius muscle in patients with spinal accessory neuropathy

• Three patients with spinal accessory neuropathy showed increased FDG uptake in the ipsilateral trapezius muscle.
• It is the first clinical report of glucose hypermetabolism in denervated muscle.
• Increased accumulation of FDG in muscle should not be ignored and may in fact be indicative of an underlying neuropathy.

To investigate 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) signal changes of denervated muscles in patients with electrophysiologically confirmed neuropathy.MethodsThis is a case series of three cancer patients who were referred to the electromyography laboratory in 2013 due to shoulder discomfort after surgery including neck dissection. Spinal accessory neuropathy was diagnosed based on electrophysiological studies. Patients' medical history, electrophysiological data, and FDG-PET images were reviewed retrospectively. Mean standard uptake values (SUV) of trapezius muscles were measured.ResultsThe patients (3 men, aged 61–78 years) showed spinal accessory neuropathy with different degrees of severity. In all patients, preoperative or postoperative FDG-PET showed increased FDG uptake in the ipsilateral trapezius muscle. These results were compatible with previously reported glucose hypermetabolism in denervated skeletal muscles.ConclusionThis is the first clinical report of increased FDG uptake by denervated muscles in electrophysiologically confirmed neuropathy.